[cfe-commits] [PATCH] Add multiple prefixes to Option.

[Michael Spencer]

On Fri, Oct 19, 2012 at 12:48 PM, Daniel Dunbar <daniel at zuster.org> wrote:
> On Fri, Oct 19, 2012 at 12:39 PM, Michael Spencer <bigcheesegs at gmail.com> wrote:
>> On Fri, Oct 19, 2012 at 10:38 AM, Daniel Dunbar <daniel at zuster.org> wrote:
>>> Hi Michael,
>>>
>>> I understand what this patch does, but I don't really understand the
>>> motivation for it, yet.
>>>
>>> Why is this the "main feature" needed for sane gnu-ld and link command
>>> line support?
>>>
>>> It seems to me, that what you really need for those is a completely
>>> separate option parsing table. I can see how this patch could be
>>> useful if you wanted to accept the same options for the link.exe
>>> parsing just with a '/' at the front, but that doesn't seem right to
>>> me. It seems to me that the link.exe parsing or cl.exe parsing would
>>> end up using a completely separate parsing table.
>>>
>>> Can you explain?
>>>
>>>  - Daniel
>>
>> The option tables would be completely separate. This is needed because
>> link supports both / and - prefixes for all options. gnu-ld supports -
>> and -- for almost all options.
>
> If the option tables are separate, can't we dramatically simplify this
> patch by making this a feature of the option table then? So that an
> option table can opt in to explicitly specifying all prefixes, and
> then we don't need to clutter up the Clang/GCC option table. Option
> tables which didn't opt-in to that would be required to supply a list
> of possible prefixes.
>
>  - Daniel

This would work if clang and gcc used only one prefix. There are 36
options that use both - and --, and 103 that use --.

I can simplify this patch by defaulting to - via tblgen and only
changing those 139 options that are special.

- Michael Spencer

>> From the ld man page:
>>
>> "For options whose names are multiple letters, either one dash or two
>> can precede the option name; for example, -trace-symbol and
>> --trace-symbol are equivalent. Note---there is one exception to this
>> rule. Multiple letter options that start with a lower case 'o' can
>> only be preceded by two dashes. This is to reduce confusion with the
>> -o option. So for example -omagic sets the output file name to magic
>> whereas --omagic sets the NMAGIC flag on the output."
>>
>> - Michael Spencer
>>
>>>
>>> On Thu, Oct 18, 2012 at 3:53 PM, Michael Spencer <bigcheesegs at gmail.com> wrote:
>>>> Hi ddunbar,
>>>>
>>>> This patch adds support for multiple prefixes per option. This is the main feature needed for sane gnu-ld and link command line support.
>>>>
>>>> Most of the ["-"]'s can be refactored to a common class in tablegen, but I have a few more widespread tablegen changes I want to make before doing all the refactoring needed.
>>>>
>>>> http://llvm-reviews.chandlerc.com/D69
>>>>
>>>> Files:
>>>>   include/clang/Driver/Arg.h
>>>>   include/clang/Driver/CC1AsOptions.h
>>>>   include/clang/Driver/CC1AsOptions.td
>>>>   include/clang/Driver/CC1Options.td
>>>>   include/clang/Driver/OptParser.td
>>>>   include/clang/Driver/OptTable.h
>>>>   include/clang/Driver/Option.h
>>>>   include/clang/Driver/Options.h
>>>>   include/clang/Driver/Options.td
>>>>   lib/Driver/Arg.cpp
>>>>   lib/Driver/ArgList.cpp
>>>>   lib/Driver/CC1AsOptions.cpp
>>>>   lib/Driver/Driver.cpp
>>>>   lib/Driver/DriverOptions.cpp
>>>>   lib/Driver/OptTable.cpp
>>>>   lib/Driver/Option.cpp
>>>>   lib/Driver/Tools.cpp
>>>>   lib/Frontend/CompilerInvocation.cpp
>>>>   utils/TableGen/OptParserEmitter.cpp